Comparison of the noise produced by the polymer and bronze P1566 propellers in the cavitation tunnel.

The paper presents the selected results of the international project called Nextprop, carried out in the framework of the European Defence Agency, which main goal was to examine elastic polymer propellers. The article includes the results of the comparative analysis in terms of the noise produced by two propellers: (1) the classical one made from Nickel Aluminium Bronze (NAB) and (2) the novel elastic counterpart manufactured from polyamide. The measurements were taken in the CTO cavitation tunnel in Gdańsk, Poland. The obtained results allow the following highlights to be formulated: the novel flexible propellers seem to be a promising solution for the new ships, especially in terms of energetic efficiency and produced noise, i.e. lower sound pressure level has been obtained for the new polymer propeller and larger advance speed for the same rotational speeds has been received for the new propeller compared to the classical metal counterpart. At the beginning, the introduction with the results of state-of-the-art analysis is presented. Then, the description of the measurement stand and examined propellers with seizing conditions is included. Next, the obtained results are illustrated and discussed. At the end, the conclusions with the draft of the future research are presented.